InStyle.com: Do They Really Work? 16 Big-Claim Beauty Products Put To the Test

Diamond-Tipped Exfoliator

The Claim: Want a youthful glow without the sun's help? Behold, an at-home microdermabrasion tool equipped with three diamond-encrusted tips to brighten and smooth (not scratch) skin and suction power to eliminate flakes and dead cells that dull the surface. Used once a week, it beats your gooey, fruity-smelling scrub in the performance department. Expert Opinion: "If you're going to invest in an at-home skin-care device, this is where I recommend you spend your money," says dermatologist Joshua Zeichner. In fact, utilized on a high setting with a medium tip, he says, "it provides a professional-quality microdermabrasion," though at first it's best to start with the lowest setting and finest tip to gauge your sensitivity. Our Take: "It makes quick, clean work of exfoliating. I did one side of my face and immediately saw a difference in texture—even after I put on makeup, that side of my face looked more even," remarks one staffer. "After a few weekly sessions I did think my skin was brighter, and it definitely felt softer." A word of caution: Even on the lowest setting, with a fine tip, the abrasiveness of the tool may not be negligible. Says another staffer, "After several passes over one cheek, my skin started to tingle a bit, so I was careful to not linger over certain spots." Riiviva Microderm, $299; riiviva.com.

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Is your bathroom cabinet filled with beauty products you’ve used once—and never again? Yeah, we thought so. To make sure your next purchase lives up to the hype, we gathered a team of seen-it-all experts and up-for-anything staffers to put a slew of innovative offerings to the test. From whitening teeth while washing dishes to flat-ironing hair at the beach (seriously), the trials are over and the results are in. Check out which of these goodies are worthy of your investment—and a spot on your shelf.The Claim: From inventive stylist Sarah Potempa, who last year sent strands spinning in her rotating Beachwaver curling iron, comes a portable (and totes adorable) mini rechargeable iron. Heating up to 450 degrees and staying toasty for 30 minutes, it allows you to style any time, any place, even if there's no outlet nearby. Expert Opinion: The 7½-inch-long tool is ideal for small jobs, like "taming frizzy bangs or curling your ends," says N.Y.C. stylist Kattia Solano. But if you want to even out an entire head of long, thick hair, you'll probably need an iron with larger plates that will sizzle for more than half an hour, she says. Our Take: "It's great in a pinch," says one tester who flat-ironed swelling strands around her hairline on a humid beach in Barbados. It's also awesome for "smoothing the top layer of hair the day after a blowout." The Jet-Setter by Sarah Potempa, $99; joyus.com.

The Claim: They're not gels, and they're not traditional polishes. Confused? Consider Vinylux the sweet spot between the two. A double layer of color and a clear topcoat hold tight to nails for seven days without chipping and can be easily removed in seconds with cotton and acetone. What's behind the staying power? "The color blends contain particles that bind to the keratin proteins in nails, while cross-linked polymers in the topcoat cause it to strengthen when exposed to natural light to prevent chipping, explains David Valia, CND research and development nails director. Expert Opinion: Consider manicurist Dawn Sterling a superfan. "These formulas are easy to apply, and they stick to nails longer than typical polish," she says. "On me the finish lasted about five days, which is impressive since I'm constantly using my hands." Our Take: We give it two painted thumbs up. A week of chip-free nails had our testers marveling—one reached the 10-day mark and exclaimed, "I'm a lifer!" The best part? No acetone finger baths required. CND Vinylux in Midnight Swim, Decadence, Dark Dahlia, and Weekly Top Coat, $10 each; cnd.com for salons.

The Claim: Whether you're looking to mask gray or telltale roots, this convenient kit lets you keep your secret. Ions in the powders help them cling to the surface of your hair for full coverage that lasts until you shampoo. And unlike some matte, one-dimensional touch-up products, the brand's four shades contain multitonal, light-reflecting pigments that produce shiny, natural-looking color. Expert Opinion: "The powders have a hint of shimmer, which helps keep the tone from looking artificial," says N.Y.C. stylist Matt Fugate, who also gives major props to the "elegant and beautiful" compacts. "To get the most precise application possible, you can tap the smaller end of the enclosed brush directly over roots." Our Take: A brunet staffer with overgrown highlights uses the honey hue to conceal mousy strands around the hairline. "It takes a few minutes—I have to work with small sections and go over each of them several times to get a dense dose of color. But the finish is totally believable!" Sometimes she switches things up, using the brown powder to darken roots for an ombré effect. "The powders don't smudge and last for about six to eight hours before they slowly start to fade." Color Wow Root Cover Up for blond hair and for dark brown hair, $30 each; ulta.com.

The Claim: This system—which comes with a rechargeable base, a mouthpiece, 10 vials of hydrogen peroxide gel, and a lip-protecting balm—is meant to make your smile five shades brighter in five days. How it works: After sweeping the protective salve over your lips, apply the gel onto your teeth, activate the device, and insert the mouthpiece; wait eight minutes, then remove it, add more gel, and repeat the process three times. Make this your routine for five straight days to see full results. "There's an LED inside the mouthpiece," says creator Jonathan Levine, an N.Y.C. dentist. "When trapped with heat inside the mouth, it accelerates the whitening process" and doesn't cause sensitivity in users. Expert Opinion: Sleek and user-friendly, it brightens after five days, "though results may vary from person to person," says N.Y.C. dentist Emanuel Layliev. But keep in mind, he says, "at-home systems are never as high in peroxide concentration as professional ones for safety reasons, so this is best used after an in-office whitening procedure to maintain the look." Our Take: Once the piece was put in place, our tester got nervous. "I wasn't sure I'd make it through the first eight minutes, let alone 32, but it wasn't that uncomfortable, and once I got busy the time flew by," she says. "I washed dishes, watched TV, and filed my nails while the gel did its thing. Best of all, my teeth were three shades whiter in two days." Sensitivity issues? "I had some tingling afterward." GLO Brilliant Personal Teeth Whitening Device, $199; sephora.com.

The Claim: These shimmery appliqués promise to adhere for up to 16 hours and don't shed bits of glitter onto your face the way some loose shadows do. To apply, peel off the plastic covering from the colorful side, then stick the strip onto a clean lid; to remove the paper backing from the exposed side, moisten with a wet swab until it slips off. Expert Opinion: If you're shaky with pens, "it's a good way to guarantee symmetry between both eyes," says N.Y.C. makeup pro Troy Surratt. For the best look, "place stickers as close to lash lines as possible, and use liquid liner to fill in gaps." Our Take: Our tester almost gave up after three fails, then realized her mistake: "Since I didn't remove my eye makeup completely, my skin was oily," she says. "Once I wiped my lids clean, the appliqués stuck, and they stayed in place until I peeled them off before going to bed." Her favorite part was that "people at the office kept asking me how I was able to draw such perfect lines!" Violent Eyes in Jet Black Glitteratti and Smoky Metal Glitteratti, $10 each; violentlips.com.

The Claim: These sticks aim to deliver rich color that lasts all day, and they're loaded with vitamins A, C, and E as well as shea butter to help give lips a fuller effect and keep them hydrated for up to 12 hours. Expert Opinion: Add one to your shopping cart. "They're very moisturizing, and the shades have a bit of a sheen, which helps give the appearance of a fuller mouth," says N.Y.C. makeup artist Anthea King. The super-creamy formula also offers full coverage and "leaves a light stain of color, even after hours of wear." Our Take: It's no shot of Restylane, but one happy staffer loves how a terra-cotta version makes her lips look "more defined and slightly plumper, with zero feathering." Another tester slicked on a coral hue, then "drank two cups of coffee, ate a pear, chewed gum, and had a bowl of soup." The verdict? "The color didn't budge, and my lips still felt hydrated." Elizabeth Arden Beautiful Color Moisturizing lipstick in Neoclassic Coral and Red Door Red, $25 each; elizabetharden.com.

The Claim: Ever layer foundation over a parched complexion? Hello, streaks! Enter this water-based primer, designed to flood your skin with moisturizing glycerin and sodium hyaluronate along with botanical extracts to create an even, plump surface. Bonus: The formula keeps your base anchored for hours. Expert Opinion: Most long-wear foundations are highly pigmented and settle into skin quickly, so they "get draggy" as you apply them, says makeup pro Troy Surratt. "But this gel-like primer gives the surface some slip to help your base glide on and blend easily." It's also a fantastic moisturizer for someone who doesn't like "a heavy cream under makeup," he notes. Our Take: According to one tester, the application isn't exactly smooth. "It feels like I'm rubbing Jell-O on my cheeks, and it leaves a slightly tacky residue," she says. "But it does immediately make my skin look plump and dewy." During a 90-degree day in New York, this staffer decided to conduct an experiment, priming just one side of her face before applying her foundation. After six hours outside, "the half with primer looked fresh, as if I'd just put on my makeup," she says. "The skin on the other side was uneven and tired-looking." Illamasqua Hydra Veil Rehydrating Gel, $40; sephora.com.

The Claim: Created by dermatologist Audrey Kunin, this anti-cellulite cream employs a mix of plant-based ingredients, plus a complex of proteins and lipids that work together to shrink fat cells and help strengthen skin-firming collagen. After applying the cream on dimpled areas (think thighs, butt, and belly) twice a day for two weeks, you not only will see smoother skin but will also lose up to an inch from the targeted area. Expert Opinion: "This contains methyl xanthine, an ingredient that, like caffeine, can help shrink and dehydrate fat cells, but only temporarily," says N.Y.C. dermatologist Joshua Zeichner. In other words, don't skip your sit-ups and squats. "This cream is hydrating, and after two weeks I did notice that my tester's skin showed a modest improvement in tone and texture—but it's not going to get rid of a muffin top." Our Take: Several ladies slathered on the cream for 14 days. Noted one: "It instantly made my legs seem smoother and more toned." Another sneaky tester treated only one leg, then flashed both limbs in front of her husband and asked which one looked better. "Smart guy that he is, he first swore both looked 'perfect,'" she says. "But he was able to pick out the slightly slimmer one." Derma Doctor Shrinking Beauty Firming, Sculpting, and Toning lotion, $58; dermadoctor.com.

The Claim: If you're coveting Rihanna's stiletto tips, this is the tool for you. The curved shape of the stainless-steel file glides effortlessly around the edges of nails to form any shape, from square to almond, in seconds. Expert Opinion: "I've never seen anything like it," says N.Y.C. manicurist Dawn Sterling. "A lot of women have a hard time crafting oval shapes with a straight file, but this makes it easy. And you can work it around long or short nails." Diagrams on the back of the package will help you get started. Our Take: It's 50/50. One tester finds it "comfortable to hold" and says, "I ran the corners of my nail over the length of the file and had a rounded tip in less than a minute." Another found it harder to handle, saying, "I'm much faster with my regular file." Every Beauty 3-in-1 nail file, $5; everybeautybrand.com.

The Claim: The tinted, water-resistant gel contains tiny fibers that adhere to hairs and help bulk up skimpy brows on the spot. The Medium/Deep shade matches brunet and black strands, while the Light/Medium is meant to deepen blond hairs. Here's to darker, fuller, natural-looking eye frames! Expert Opinion: It has a slight staining effect on skin and hair, "which makes brows appear more dense," says makeup pro Troy Surratt, who adds that sweeping the brush up through strands doesn't take as much precision (or time) as dabbing on a powder, and "the results look more realistic than pencil strokes." Our Take: Gimme Brow? How about Gimme Wow? "I absolutely adore this product—it grooms my thin brows and beefs them up in just a couple of strokes," says a staffer. "I don't even need a mirror to sweep it on," says another. "The gel lightly tints and doesn't smear a bit once it's dry." Benefit Gimme Brow in Medium/Deep, $22; benefitcosmetics.com.

The Claim: News flash: Nail art is having a major moment, and this kit aims to make dressing up your digits ridiculously easy and fun. You just paint a nail with the enclosed polish, then dot the white glue over areas you want to cover in foil. Wait a few minutes until the glue turns clear, then press a foil sheet onto the nail (the box contains 30 of them). Rip it off, and voilà! Expert Opinion: As a manicurist, Dawn Sterling quickly got the hang of it and "loves the fashion-forward look it offers" but admits that someone who isn't skilled at doing her own nails might find the technique "tricky." Her best tip for foolproof results: When it's time to let 'em rip, "yank the foil off swiftly and in one direction." Our Take: The finish "looks so cool," but you must be "very patient," warns a tester. "If you don't let the glue turn completely clear before pressing on the foil, the surface will be goopy when you pull off the sheet, and you'll be left with smudges." Ciaté Very Colourfoil manicure kit in Wonderland, $19; sephora.com.

The Claim: This set relies on a slender rechargeable tool and high-tech topical eye and lip treatments to deliver smoother, plumper-looking skin in two weeks. Here's the scoop: Apply the products. Turn on the device and massage it over the areas for 60 seconds each. The wand emits ultrasound energy, which causes the microspheres inside the formulas to vibrate and "create channels in the upper layer of skin and lips so the other ingredients—like retinoids, hyaluronic acid, vitamin C, and peptides—can penetrate deep to do their job," says Colette Courtion, chief beauty innovator at Jenu Biosciences. Expert Opinion: Dermatologist Joshua Zeichner believes that ultrasound waves can enhance product penetration. "After two weeks of nightly use, the skin around my tester's eyes was far more hydrated," and there was a moderate softening of fine lines. Our Take: The gadget "tickles" and "feels like a massage," says a staffer who in 14 days reported "super-moisturized skin but only ever so slightly less visible crow's-feet." The tester notes the lip serum is "pretty greasy, but my mouth looks a bit fuller after just a minute of using the device." And, she says, the plump, hydrated effect can last for hours. Jenu Active-Youth Skincare system, $249; jenu.com.

The Claim: Don't blink or you'll miss this trick. After applying the sheer base, the fluid evaporates and featherweight pigments leave a flawless finish and an even complexion all day. Expert Opinion: Love that no-makeup makeup look? You've found the right formula. The powdery pigments create a refined, matte surface, says makeup pro Troy Surratt. "But because it doesn't offer a ton of coverage, it probably works best on someone who already has fairly smooth skin." Our Take: Our tester also enjoys the way the foundation feels: "It's as if I'm not wearing makeup. And even though it doesn't mask my pimples, it makes ruddy patches disappear." L'Oréal Paris Magic Nude Liquid Powder Makeup in Light Ivory, $13; drugstore.com.

The Claim: Not only does it deliver a sleek, speedy blowout, but it's eco-friendly too! In addition to an insanely strong engine (we're talking an air flow of 80 miles per hour), stylist and creator Harry Josh included an ion generator that, when clicked on, releases negative ions to neutralize frizz. On the green front, the tool works with a dual filtration system that prevents dust particles from getting into the motor and decreasing its efficiency, so the device uses less energy overall. Expert Opinion: "I like how small, lightweight, and powerful it is," says stylist Matt Fugate. Another fave feature? The cool-shot button. "It chills air really fast. I use it when I'm almost done drying strands to seal cuticles and lock in the look." Our Take: "It cuts 15 minutes from my usual 35-minute drying time and gets my long, thick hair really smooth," says a staffer, who didn't notice a big change in volume when she turned off the ion generator. Our testers say they'd "totally buy it"—if they ever recover from the sticker shock. Harry Josh Pro Tools Dryer 2000, $300; hairenvy.com.

The Claim: Want a youthful glow without the sun's help? Behold, an at-home microdermabrasion tool equipped with three diamond-encrusted tips to brighten and smooth (not scratch) skin and suction power to eliminate flakes and dead cells that dull the surface. Used once a week, it beats your gooey, fruity-smelling scrub in the performance department. Expert Opinion: "If you're going to invest in an at-home skin-care device, this is where I recommend you spend your money," says dermatologist Joshua Zeichner. In fact, utilized on a high setting with a medium tip, he says, "it provides a professional-quality microdermabrasion," though at first it's best to start with the lowest setting and finest tip to gauge your sensitivity. Our Take: "It makes quick, clean work of exfoliating. I did one side of my face and immediately saw a difference in texture—even after I put on makeup, that side of my face looked more even," remarks one staffer. "After a few weekly sessions I did think my skin was brighter, and it definitely felt softer." A word of caution: Even on the lowest setting, with a fine tip, the abrasiveness of the tool may not be negligible. Says another staffer, "After several passes over one cheek, my skin started to tingle a bit, so I was careful to not linger over certain spots." Riiviva Microderm, $299; riiviva.com.

The Claim: Packed with moisturizing emollients, styling polymers, and the brand's patented molecule OFPMA, this serum smooths hair to make blowouts less of a bicep-burning workout. And since it doesn't contain heavy silicones, which can weigh down strands, it promises to leave locks bouncy whether you apply it while they are wet or dry. Expert Opinion: "Love it!" says Fugate. "The formula absorbs easily into hair," and when applied before a blowout, "it makes hair shiny and gives it a bit of hold." Our Take: One staffer worked a handful into thick, wavy, wet strands before hitting them with heat and reports, "It made drying each section much easier. And though it didn't eliminate frizz entirely, the formula is so light, it didn't feel like I had any product in my hair at all." Still, a drop was too much for another tester's dry, fine strands, leaving them "just a tad stringy." Living Proof Satin Hair serum, $29; sephora.com.